MSEARCH-49 Caching for language configs

For distributed caching can be used Hazelcast In-memory caching. It is fast, reliable and scalable solution, that can be used for different clusters - AWS, Kubernetes and etc.

Required dependencies for mod-search project:

</properties>
  ...
  <hazelcast.version>4.2</hazelcast.version>
  ...
</properties>
</dependencies>
  ...
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-cache</artifactId>
  </dependency>
  <dependency>
    <groupId>com.hazelcast</groupId>
    <artifactId>hazelcast-all</artifactId>
    <version>${hazelcast.version}</version>
  </dependency>
</dependencies>

Hazelcast cache can be configured using XML, YAML or using Java.

Spring configuration

Configuration class should looks like:

package org.folio.search.configuration;

import com.hazelcast.config.ClasspathYamlConfig;
import com.hazelcast.config.Config;
import com.hazelcast.config.EvictionConfig;
import com.hazelcast.config.EvictionPolicy;
import com.hazelcast.config.InMemoryFormat;
import com.hazelcast.config.MapConfig;
import com.hazelcast.config.MaxSizePolicy;
import lombok.RequiredArgsConstructor;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@RequiredArgsConstructor
public class CacheProperties {

  @Bean
  public Config hazelcastConfig(@Value("${HAZELCAST_CONFIG_TYPE:multicast}") String configType) {
    return new ClasspathYamlConfig(String.format("hazelcast-%s.yaml", configType))
      .addMapConfig(new MapConfig("testHazelcastCache")
      .setInMemoryFormat(InMemoryFormat.BINARY)
      .setEvictionConfig(new EvictionConfig()
        .setEvictionPolicy(EvictionPolicy.LRU)
        .setMaxSizePolicy(MaxSizePolicy.PER_NODE)
        .setSize(1000))
      .setTimeToLiveSeconds(600));
  }
}

Common cache settings can be stored in Java configuration, environment specific can be defined using configuration properties in Java or as external YAML configurations in project:

hazelcast-k8s.yaml

hazelcast:
  instance-name: hazelcast-cache
  network:
    join:
      multicast:
        enabled: false
      kubernetes:
        enabled: true
        service-name: mod-search
        namespace: falcon

Which is equal to Java configuration:

config.getNetworkConfig().getJoin().getMulticastConfig().setEnabled(false);
config.getNetworkConfig().getJoin().getKubernetesConfig().setEnabled(true)
  .setProperty("namespace", "falcon")
  .setProperty("service-name", "mod-search");

Kubernetes configuration

Using Kubernetes API requires granting certain permissions. To grant them for 'default' service account in 'default' namespace execute the following command.

https://raw.githubusercontent.com/hazelcast/hazelcast-kubernetes/master/rbac.yaml

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: hazelcast-cluster-role
rules:
  - apiGroups:
    - ""
    resources:
      - endpoints
      - pods
      - nodes
      - services
    verbs:
      - get
      - list

---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: hazelcast-cluster-role-binding
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: hazelcast-cluster-role
subjects:
  - kind: ServiceAccount
    name: default
    namespace: default

Load balancer should allow to pods communicate with each other using port 5071

apiVersion: v1
kind: Service
metadata:
  name: mod-search
spec:
  type: LoadBalancer
  selector:
    app: mod-search
ports:
  - name: hazelcast
    port: 5701
  - name: app
    port: 8081